Systems and methods for non-flammable indication of incendivity

ABSTRACT

Incendivity test systems and methods are disclosed. Incendivity test systems include a non-flammable gas mixture and a test article. The non-flammable gas mixture includes a thermally reactive reagent that is formulated to thermally react to produce a reaction product. Incendivity test systems also include an energy source configured to apply an energy discharge such as a simulated lightning strike to the test article. Incendivity test systems also include a detection device configured to measure an indicator species in the non-flammable gas mixture (e.g., the thermally reactive reagent and/or the reaction product). Incendivity test methods include contacting the test article with the non-flammable gas mixture, applying the energy discharge to the test article, and then measuring the amount of the indicator species and determining the incendivity of the test article in response to the energy discharge based upon the amount of the indicator species.

RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.15/214,214, entitled “SYSTEMS AND METHODS FOR NON-FLAMMABLE INDICATIONOF INCENDIVITY,” now U.S. Pat. No. 10,145,834, filed on Jul. 19, 2016,the complete disclosure of which is hereby incorporated by reference.

FIELD

The present disclosure relates to systems and methods for non-flammableindication of incendivity.

BACKGROUND

In many situations, apparatuses must operate in potentially hazardousconditions, such as where a fuel mixture may be ignited by uncontrolledoperating or environmental conditions. For example, vehicles, includingaerospace vehicles, typically operate with a fuel that must bemaintained in a safe condition during storage and use. The ignitionhazard should be minimized even when the vehicle is subject touncontrolled events such as an accident, electrical malfunction, alightning strike, or static electrical discharge. Other applicationsrequiring ignition hazard consideration include fuel transport, fuelstorage, mining operations, chemical processing, metal fabrication,power plant construction and operation, and operations which involvecombustible particulate such as sawdust, metal, flour, and grain.

Design of apparatuses exposed to ignition hazards typically involvesreducing the likelihood of ignition, containing the ignition hazard,and/or withstanding the ignition hazard. Test systems may facilitate orverify the design of a component by simulating or applying ignitionhazard precursors such as heating, a simulated lightning strike, orother electromagnetic effects (e.g., arcing, electrostatic discharge,heating, and/or hot particle ejection).

In the aerospace industry, the Federal Aviation Administration (FAA)requires ignition source tests for components potentially exposed tofuel-vapor environments (specified in SAE ARP 5416A (SAE Aerospace)).One test method is the photographic method and another method is theignitable mixture (flammable gas) test method. The photographic methodsubjects a test article to an ignition hazard precursor (e.g., simulatedlightning strike) in a darkened chamber to observe the light produced byarcs (if any) emitted by the test article. The photographic method issuitable for arcs, which are relatively quick and bright, but not wellsuited for hot particles, other heat sources, or ignition hazards thatimpart energy more slowly or which do not have corresponding lightemission.

The ignitable mixture (flammable gas) test method subjects the testarticle to the ignition hazard precursor in a flammable atmospherewithin a combustion chamber (which may be referred to as a combustionvessel or a bomb). If the test article produces an ignition hazard, theflammable atmosphere explosively ignites in the combustion chamber. Thecontained explosion may be detected by various techniques (e.g., bydetecting the pressure change, the light, the heat, and/or the sound ofthe explosion). The ignitable mixture test method has the advantage ofbeing more realistic than the photographic method, in that the flammableatmosphere reacts in the same manner (thermal reaction) as does theatmosphere that may contact the test article in actual use. The primarydisadvantage of the ignitable mixture test method is the use of theflammable atmosphere, which requires care in the preparation andfabrication of the combustion chamber, and care in handling theflammable gas. Some test articles may be quite large (e.g., componentsor the entirety of a wing fuel tank of an aircraft) and have consequentgreater demands for the safe operation of the combustion chamber and thesafe handling of the flammable atmosphere. Additionally, because anignition hazard causes the flammable atmosphere to be consumed, theignitable mixture (flammable gas) test method produces merely apass-fail result.

SUMMARY

Incendivity test systems and methods are disclosed. Incendivity testsystems include a non-flammable gas mixture and a test article. Thenon-flammable gas mixture is non-flammable yet includes a thermallyreactive reagent that is formulated to thermally react to produce areaction product without self-propagating combustion or explosion. Forexample, the non-flammable gas mixture may be a mixture below the lowerflammability limit of the thermally reactive reagent. Incendivity testsystems also include an energy source configured to apply an energydischarge such as a simulated lightning strike to the test article.Incendivity test systems also include a detection device configured tomeasure an indicator species in the non-flammable gas mixture (e.g., thethermally reactive reagent and/or the reaction product).

Incendivity test methods include contacting a test article with anon-flammable gas mixture that includes a thermally reactive reagent.Incendivity test methods include applying an energy discharge to thetest article while the test article is in contact with the non-flammablegas mixture. After applying the energy discharge, incendivity testmethods include measuring an amount of one or more components of thenon-flammable gas mixture (i.e., one or more indicator species) thatrepresents an amount of the thermally reactive reagent that reacted inresponse to applying the energy discharge. Incendivity test methods alsoinclude determining an incendivity of the test article in response tothe energy discharge based upon the amount of the thermally reactivereagent that reacted in response to applying the energy discharge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an incendivity test systemaccording to the present disclosure.

FIG. 2 is a schematic representation of an example of an incendivitytest system according to the present disclosure.

FIG. 3 is a schematic representation of another example of anincendivity test system according to the present disclosure.

FIG. 4 is a schematic representation of incendivity test methodsaccording to the present disclosure.

DESCRIPTION

The systems and methods described herein can be used to test forignition hazards without the limitations of the traditional ignitionhazard testing techniques. For example, the herein-described systems andmethods can be sensitive to various types of ignition hazards withoutrequiring a flammable atmosphere. More specifically, incendivity testsystems and methods of the present disclosure are similar to ignitablemixture (flammable gas) test systems and methods, but fundamentallydiffer by utilizing a non-flammable gas mixture. The ignitable mixture(flammable gas) test systems and methods would not function to produce aresult (explosive combustion) without the flammable gas.

With the incendivity test systems and methods of the present disclosure,the test article may be subject to a simulated ignition risk event(e.g., a simulated lightning strike) and if the ignition risk eventgenerates an ignition source at the test article, some of thenon-flammable gas mixture will react. The non-flammable gas mixture isselected, configured, and/or formulated such that an ignition sourcewill not generate a self-propagating combustion front (i.e., the gaswill not explode due to the ignition source). Only a portion of thenon-flammable gas mixture, a portion near the ignition source, willreact to the ignition source. The reaction due to the ignition sourcemay be detected by analyzing the gas contents after the ignition riskevent. By examining the degree or amount of chemical change to thenon-flammable gas mixture, the risk of ignition due to an energy release(the ignition risk event) may be quantified. The risk of ignition may bea binary value (yes/no, pass/fail, etc.) or a value related to thedegree or amount of chemical change to the non-flammable gas mixture.Hence, the incendivity test systems and methods of the presentdisclosure may provide more information about the ignition source (suchas the amount of energy released) than traditional ignition hazardtesting techniques such as the photographic method or the ignitablemixture (flammable gas) test method.

FIGS. 1-4 illustrate incendivity test systems and methods. In general,in the drawings, elements that are likely to be included in a givenembodiment are illustrated in solid lines, while elements that areoptional or alternatives are illustrated in dashed lines. However,elements that are illustrated in solid lines are not essential to allembodiments of the present disclosure, and an element shown in solidlines may be omitted from a particular embodiment without departing fromthe scope of the present disclosure. Elements that serve a similar, orat least substantially similar, purpose are labelled with numbersconsistent among the figures. Like numbers in each of the figures, andthe corresponding elements, may not be discussed in detail herein withreference to each of the figures. Similarly, all elements may not belabelled or shown in each of the figures, but reference numeralsassociated therewith may be used for consistency. Elements, components,and/or features that are discussed with reference to one or more of thefigures may be included in and/or used with any of the figures withoutdeparting from the scope of the present disclosure.

FIG. 1 illustrates an incendivity test system 10 that may be utilized totest the incendivity of a test article 20 that is subject to an ignitionrisk event (an energy discharge). The test system 10 includes anon-flammable gas mixture 30 to sense an ignition source 24 generated atthe test article 20, an energy source 26 configured to apply the energydischarge to the test article 20 to potentially generate the ignitionsource 24, and a detection device 50 configured to measure an amount ofone or more indicator species in the non-flammable gas mixture after theenergy discharge. Incendivity is the ability to cause ignition of aflammable substance such as a flammable environment. Hence, theincendivity test system 10 may be referred to as a flammability testsystem, an ignition risk test system, and/or an ignition hazard testsystem.

Generally, the test system 10 is configured to identify the presence of,and/or verify the absence of, ignition sources 24 associated withequipment, devices, and/or apparatuses operated in a combustibleenvironment and/or near combustible materials. More specifically, thetest system 10 may be configured to detect ignition sources 24 generatedon the test article 20 by the ignition risk event (the energy dischargegenerated by the energy source 26) that simulates actual and/orpotential operating conditions and/or uncontrolled events. For example,the energy discharge may be a simulated lightning strike, heat, anelectrical discharge, an electrical voltage, an electrical current, anelectrical arc, and/or a combustion event (e.g., heat, flame, fire).Examples of ignition sources 24 that may be generated include anelectrical arc, a spark, a hot surface, a hot particle ejection, anelectrostatic discharge, and a flame.

The test article 20 may be equipment, a device, and/or an apparatus thatmay operate near combustible materials and/or in combustibleenvironments where uncontrolled ignition sources could be hazardous. Thetest article 20 also may be a portion, a component, and/or a model ofsuch equipment, device, and/or apparatus. The equipment, device, and/orapparatus may be associated with one or many industries such astransportation, aerospace, chemical processing, petroleum production,mining, power production, forestry, and/or agriculture. For example, thetest article 20 may be, may represent, and/or may be a component of atransport vehicle (e.g., a truck, an aircraft, a rocket), an aerospacecomponent, an aircraft skin, an aircraft frame, a wing, a fuel handlingcomponent, a fuel system, a fuel tank, a fuel pump, a ventilatorcomponent, a ventilation system, mining equipment, dust handlingequipment, and/or an electrical enclosure. Generally, the test article20 has a solid form, though the test article 20 may include liquidand/or gaseous elements. The test article 20 may include one or more ofmetal, aluminum, plastic, and fiber-reinforced composite material.

The energy source 26 is configured to discharge energy into, at, and/orto the test article 20 to test whether the discharged energy generatesthe ignition source 24 at the test article 20. The energy source 26 maybe a simulated or actual operating condition such as a lightning strike,an electrical charge simulating static charge build-up, heat simulatingenvironmental conditions (e.g., ambient operating conditions, proximatedecomposition and/or combustion, and/or operation of a neighboringengine), and/or electromagnetic radiation simulating an operatingenvironment. The energy source 26 may include, and/or may be, alightning simulator, a heater, a heat source, a flame, an electricalpower source, an electrical voltage source, an electrical currentsource, and/or an electrical arc generator. In FIG. 1, the dischargedenergy is indicated by energy transmission 28. Energy transmission 28may be via a conduit, a cable, and/or a conductor, and may span a gapbetween the energy source 26 and the test article 20. The energy source26 may be separated and/or external from the test article 20 (asillustrated in the example of FIG. 1). In some embodiments, the testarticle 20 may include the energy source 26 and/or the test article 20may be the energy source 26 (for example, a test article 20 may be abattery and the test system 10 may be configured to test the batteryunder normal operating conditions).

The test system 10 and/or the energy source 26 are configured to avoiddirectly reacting the non-flammable gas mixture 30 with the energydischarge. In one arrangement, the test system 10 and/or the energysource 26 may be configured to apply the energy discharge to the testarticle 20 at an application site isolated from the non-flammable gasmixture 30. For example, the energy transmission 28 may includeelectrical cables which convey a voltage and/or carry a current, andthat are electrically insulated from the non-flammable gas mixture 30.As another example, the test article 20 may include an exterior and/oran interior (which may be fluidically isolated from one another). Thenon-flammable gas mixture 30 may contact one of the exterior andinterior and the application site of the discharged energy may be on theother side (exterior or interior). More specifically, the test article20 may have an interior fluidically isolated from the exterior (e.g., atank, a chamber, a canister, a vessel) with non-flammable gas mixture 30contacting the exterior (or a portion thereof) and a flammable materialwithin the interior (for example, a flammable gas or aerosol filling theinterior, or a volatile, flammable liquid partially filling theinterior). Igniting the flammable material discharges energy as thematerial combusts. This energy may be discharged to the interior of thetest article 20 while the non-flammable gas mixture 30 is at theexterior of the test article 20 to indicate whether the energy dischargecreates any ignition sources 24 at the exterior of the test article 20.

The test system 10 may include a test chamber 12 that is configured toat least partially enclose the test article 20. The test chamber 12 maybe configured to hold the non-flammable gas mixture 30 and/orfluidically isolate the test article 20 and/or the non-flammable gasmixture 30 from an ambient environment (e.g., air). The test chamber 12may be a sealed chamber, an enclosed space, and/or a partitioned space.

In FIG. 1, the test article 20 is enclosed in the test chamber 12 withthe non-flammable gas mixture 30. The test chamber 12 may enclose theentirety or a portion of the test article 20. The non-flammable gasmixture 30 may contact the entirety or a portion of the test article 20.The test article 20 may be inserted into the test chamber 12 and/or thetest chamber 12 may be assembled around the test article 20. The testchamber 12 may partially or completely enclose one or more othercomponents of the test system 10. For example, the energy source 26, thedetection device 50, and/or a controller 70 (described further herein)may be within the test chamber 12.

The test chamber 12 may include a gas inlet port 14 and/or a gas outletport 16 configured to permit gas to enter and/or exit the test chamber12. In some embodiments, the test chamber 12 may include a single portthat serves as both a gas inlet port 14 and a gas outlet port 16. Thegas inlet port 14 and/or the gas outlet port 16 may be associated withone or more valves 18 that are configured to open and/or close the gasinlet port 14 and/or the gas outlet port 16.

The test chamber 12 may be gas tight in some configurations (e.g., whenthe gas inlet port(s) 14, the gas outlet port(s) 16, and any doors,windows, covers, etc. are closed and/or sealed). The test chamber 12 maybe configured to isolate the test article 20, the non-flammable gasmixture 30, and/or other components within the test chamber 12 fromoutside influences and vice versa. For example, the test chamber 12 maybe a gas-tight chamber, an electromagnetic shield, and/or a safetyshield. As another example, the test chamber 12 may be configured toavoid mixing of the non-flammable gas mixture 30 with the ambientenvironment.

The test system 10 may include a gas source 40 configured to supply thenon-flammable gas mixture 30 to the test article 20 and/or the testchamber 12. The gas source 40 may be fluidically connected to the testchamber 12 via the gas inlet port 14. The flow path from the gas source40 to the test article 20 and/or the test chamber 12 may include a valve18 that is configured to control the flow of the non-flammable gasmixture 30.

The test chamber 12 may be filled by flushing the test chamber 12 withthe non-flammable gas mixture 30 (e.g., by flowing several volumes ofthe test chamber 12 through the test chamber 12 in a manner to flush outthe air or other gas initially filling the test chamber 12).Additionally, or alternatively, the test chamber 12 may be filled byevacuating the air or other gas that initially fills the test chamber 12and by flowing the non-flammable gas mixture 30 into the test chamber12.

In some embodiments, the test system 10 may be configured to place thetest article 20 in contact with a flowing stream of the non-flammablegas mixture 30. Such embodiments may include the test chamber 12 todirect the stream to and/or around the test article 20 or may notinclude the test chamber 12. The stream of the non-flammable gas mixture30 may contact a portion or the entirety of the test article 20. Thestream of the non-flammable gas mixture 30 may be a recirculating ornon-recirculating stream.

The non-flammable gas mixture 30 includes a thermally reactive reagent32. The thermally reactive reagent 32 is thermally reactive, i.e., thethermally reactive reagent 32 undergoes reaction, e.g., a combustionreaction (i.e., a fuel-oxidant reaction with an oxidant 34) and/or athermal decomposition, in response to sufficient heat to produce one ormore species of reaction products 38.

Due to the presence of the thermally reactive reagent 32, thenon-flammable gas mixture 30 is thermally reactive and sensitive to theignition source 24 that may be created by the ignition risk event (theenergy discharge of the energy source 26). However, the non-flammablegas mixture 30 is selected, configured, and/or formulated to not beflammable or explosive. The non-flammable gas mixture 30 is reactiveenough to produce a measurable change in gas contents in the presence ofthe ignition source 24 without being so reactive as to produce asustained flame, self-propagating combustion, or explosion. For example,the non-flammable gas mixture 30 may be a fuel-air mixture that is toolean to support continued combustion (i.e., below the lower flammabilitylimit). Because the non-flammable gas mixture 30 does not explode,produce a sustained flame, or yield self-propagating combustion, thenon-flammable gas mixture 30 does not present a significant explosionrisk or an explosion risk that is as significant as traditionalflammable gas mixtures utilized for ignitable mixture (flammable gas)test systems.

With the non-flammable gas mixture 30 in contact with the test article20, the test article 20 may be tested for the ability to produce theignition source 24 in response to the ignition risk event (i.e., testedfor the incendivity of the test article 20) by measuring the change ingas contents of the non-flammable gas mixture 30 after the ignition riskevent. The thermal reaction of the thermally reactive reagent 32 due tothe ignition source 24 occurs through the same physical mechanism(heat-induced chemical reaction) as does a fuel vapor or othercombustible environment that may be present at the test article 20 inuse. Hence, if the thermally reactive reagent 32 sufficiently reacts inresponse to the ignition source 24, an actual combustible environmentwould be expected to react as well.

The thermally reactive reagent 32 may be a combustion fuel, i.e., areagent that combusts in the presence of the oxidant 34. The thermallyreactive reagent 32 may be a compound that thermally decomposes in thepresence of the ignition source 24. In such reaction systems, an oxidant34 may not be needed. Examples of combustion fuels include a hydrocarbonfuel, a flammable gas, molecular hydrogen, methane, propane, gasoline,kerosene, and ethylene. Other examples of the thermally reactive reagent32 include a halocarbon (a compound with a halogen-carbon bond) such asan alkyl halide, a chlorocarbon, a fluorocarbon, a bromocarbon, achlorofluorocarbon, chloroethane, and methyl bromide.

The non-flammable gas mixture 30 is generally gaseous and may includegas and/or an aerosol of liquids and/or solids (e.g., the non-flammablegas mixture 30 may include an aerosol of the thermally reactive reagent32). The thermally reactive reagent 32 may be in the form of a gas, avapor, and/or an aerosol.

The non-flammable gas mixture 30 may include the oxidant 34, inparticular if the thermally reactive reagent 32 is a combustion fuel oris otherwise selected, configured, and/or formulated to react with theoxidant 34. Together, the thermally reactive reagent 32 and the oxidant34 may be referred to as a reactive system. The oxidant 34 may be in theform of a gas, a vapor, and/or an aerosol. For example, thenon-flammable gas mixture 30 may include an aerosol of the oxidant 34.Examples of the oxidant 34 include molecular oxygen, nitrous oxide, andhydrogen peroxide. Examples of reactive systems include combustion fuelsand molecular oxygen, and halocarbons and molecular oxygen.

The non-flammable gas mixture 30 may include a diluent 36. The diluent36 is generally a gas and does not significantly participate in thereaction with the thermally reactive reagent 32 to produce the reactionproduct 38. Generally, the diluent 36 is inert and/or non-reactive. Thediluent 36 may be selected, configured, and/or formulated for lack ofreactivity with other components of the non-flammable gas mixture 30and/or for lack of interference with the reaction to produce thereaction product 38. The diluent 36 may be selected, configured, and/orformulated to quench combustion and/or a flame front in thenon-flammable gas mixture 30. For example, the diluent 36 may have ahigh heat capacity and/or a low thermal conductivity which may limit theflammability of the non-flammable gas mixture 30. Examples of thediluent 36 include an inert gas, nitrogen, argon, and helium.

Mixtures of combustion fuels and oxidants 34 have a flammability rangein which the mixture may be ignited (at a given pressure andtemperature). Outside of the flammability range, the mixture cannot beignited, without changing the conditions such as increasing thetemperature and/or the pressure. The flammability range may be expressedas a ratio of the combustion fuel to oxidant concentrations, and/or aconcentration range of the combustion fuel in an oxidant-fuel mixture.An oxidant-fuel mixture has a stoichiometric ratio for complete burningof the oxidant and the combustion fuel. If the amount of combustion fuelis below the stoichiometric amount, the mixture is called lean. If theamount of combustion fuel is above the stoichiometric amount, themixture is called rich. Unless otherwise stated, the flammability rangeas used herein is expressed as a mass concentration ratio of combustionfuel to oxidant.

The flammability range is delineated by a lower flammability limit (alsocalled a lean ignition limit) and an upper flammability limit (alsocalled a rich ignition limit). Below the lower flammability limit, theoxidant-fuel mixture does not contain enough combustion fuel to supporta self-propagating combustion wave. Above the upper flammability limit,the oxidant-fuel mixture does not contain enough oxidant to support aself-propagating combustion wave.

Examples of non-flammable gas mixtures 30 include mixtures below thelower flammability limit and mixtures above the upper flammabilitylimit. Mixtures above the upper flammability limit may be diluted bycontaminant gas (such as air) to form a flammable gas mixture (i.e.,with a lower concentration of combustion fuel that is within theflammability limits). Mixtures below the lower flammability limit maynot be transformed by common contaminant gases to form a flammable gasmixture. One example of a non-flammable gas mixture 30 that is below thelower flammability limit is a non-flammable gas mixture 30 that includesa volume fraction of ethylene of less the 2.7% (the lower flammabilitylimit at room temperature and pressure), less than 2.5%, about 2%,and/or greater than 0.1% in air. As another example, the non-flammablegas mixture 30 may include a volume fraction of chloroethane of lessthan 3.8% (the lower flammability limit at room temperature andpressure), about 1%, and/or greater than 0.1% in air. As yet anotherexample of a non-flammable gas mixture 30, methyl bromide is notgenerally flammable except in the presence of strong oxidizers or strongignition sources. The non-flammable gas mixture 30 may include a smallamount of methyl bromide, e.g., a volume fraction of 0.01%, in air.

Reaction products 38 may be the result of complete combustion of thethermally reactive reagent 32, the result of partial combustion of thethermally reactive reagent 32, the result of thermal decomposition ofthe thermally reactive reagent 32, and/or chemical species that arederived from the complete or partial combustion products and/or thethermal decomposition products. Examples of complete combustion productsinclude water and carbon dioxide (e.g., for combustion of ahydrocarbon). Examples of partial combustion products includeformaldehyde and carbon monoxide (e.g., for combustion of ahydrocarbon). Other examples of reaction products 38 (e.g., forhalocarbons) include hydrochloric acid, hydrofluoric acid, hydrobromicacid, carbonyl difluoride, carbonyl dichloride (also called phosgene andcarbon oxychloride), carbonyl dibromide (also called carbon oxybromide),molecular fluorine, molecular chlorine, and molecular bromine. Thenon-flammable gas mixture 30 may include relatively little reactionproduct 38 and/or may be essentially free of reaction product 38 priorto exposure of the non-flammable gas mixture 30 to the ignition source24.

In some embodiments, the non-flammable gas mixture 30 includes anindicator species (e.g., thermally reactive reagents 32 and/or reactionproducts 38) that is easy to identify and/or distinct from backgroundand/or contamination sources. For example, the thermally reactivereagent 32 may be a halocarbon. Halocarbons may be unique or rare in atypical environment such that the presence of the compound indicates thepresence of the non-flammable gas mixture 30. Similarly, the reactionproducts of halocarbons may be unique or rare in a typical environment.When a molecule of interest is uncommon in the background environment,the analysis of the gas components may be more sensitive to thatcomponent because of the lack of background signal and/or the lack ofbackground noise.

Non-flammable gas mixtures 30 may be selected, configured, and/orformulated such that the reaction to produce the reaction product 38occurs at or above a threshold reaction energy at suitable conditions.The threshold energy may be less than 1,000 μl (microjoules), less than500 μl, less than 200 μl, less than 100 μl, greater than 10 μl, greaterthan 50 μl, greater than 100 μl, greater than 200 μl, and/or about 200μl. Suitable conditions may include standard pressure and temperature,reduced pressure and/or temperature as compared to standard pressure andtemperature, and/or elevated pressure and/or temperature as compared tostandard pressure and temperature corresponding to operating and/orstorage conditions of the test article 20 (or equipment, devices, and/orapparatuses represented by the test article 20). Suitable conditions maysimulate environments such as operating and/or storage conditions on thesurface of the Earth (e.g., hot conditions in hot climates, coldconditions in cold climates), in the sky (e.g., cold and low pressureconditions at altitude), and/or below ground (e.g., hot conditions intunnels). For example, suitable conditions may include a temperature ofless than 200° C., less than 150° C., less than 100° C., less than 80°C., less than 50° C., less than 30° C., greater than −40° C., greaterthan −20° C., greater than 0° C., greater than 10° C., about 20° C.,and/or about 40° C. Suitable conditions may include a pressure ofgreater than 50 kPa (kilopascals), greater than 70 kPa, greater than 90kPa, greater than 100 kPa, less than 200 kPa, less than 150 kPa, lessthan 120 kPa, less than 100 kPa, about 70 kPa, and/or about 100 kPa. Theselection, formulation, and/or composition of the non-flammable gasmixture 30 and its components may affect the threshold reaction energy.The minimum reaction energy of the non-flammable gas mixture 30 may becalibrated and/or verified by subjecting the non-flammable gas mixture30 to a controlled-energy ignition source such as a controlledelectrical arc of a known ignition energy.

The non-flammable gas mixture 30 may include one or more species ofthermally reactive reagents 32, oxidants 34, and/or diluents 36.Multiple species and/or multiple reactive systems may be advantageous tobe sensitive to ignition sources of different types and/or differentenergies. For example, one reactive system (a species of thermallyreactive reagent 32 and an optional species of oxidant 34) may be mostsensitive to hot particle emissions while another reactive system may bemost sensitive to an electrical arc. In embodiments with multiplethermally reactive reagents 32, each thermally reactive reagent 32 maybe selected, configured, and/or formulated to react with at least one ofthe oxidants 34 and/or the same oxidant 34 to produce a correspondingreaction product 38.

The test system 10 includes the detection device 50 that is configuredto detect one or more indicator species of the non-flammable gas mixture30 after the ignition risk event is applied to the test article 20 incontact with the non-flammable gas mixture 30. The detection device 50is configured to detect the reaction (if any) and/or the extent of thereaction due to the ignition source 24 by detecting the indicatorspecies. The indicator species detected may be the thermally reactivereagent 32, the oxidant 34, and/or the reaction product 38. The presenceand/or an increase of reaction products 38, and/or the decrease ofreactants (e.g., the thermally reactive reagent 32 and/or the oxidant34) indicate the reaction and/or the extent of reaction of the thermallyreactive reagent 32 due to the presence of the ignition source 24.

The detection device 50 may measure an amount of one or more indicatorspecies and/or a ratio of indicator species. As used herein, thedetection, measurement and/or determination of an amount of a chemicalspecies may include detection, measurement and/or determination of thepresence, the presence above a threshold level, the quantity relative toa control component, and/or the absolute quantity. Control componentsmay be another indicator species, the thermally reactive reagent 32, theoxidant 34, the diluent 36, the reaction product(s) 38, and/or anotherchemical species in the non-flammable gas mixture 30 (before or afterreaction). For example, the detection device 50 may measure a ratio ofthe reaction product 38 to the thermally reactive reagent 32 and/or maymeasure a ratio of two reaction products 38. A ratio of the indicatorspecies to another gas component (e.g., a product to reactant ratio or aproduct to product ratio) may be more robust than detecting theindicator species alone (e.g., a ratio may be resilient to gas leaks inthe test chamber 12). Amounts and/or quantities of chemical species maybe measured and/or determined relative to mass, volume, pressure, and/ormoles (number of molecules or atoms). Unless otherwise specified,amounts and quantities are expressed in mass units (e.g., mass, massconcentration, mass ratio, etc.). Control components may be anotherindicator species

Because the non-flammable gas mixture 30 is non-flammable, only aportion of the non-flammable gas mixture 30 will react in response tothe ignition source 24. The portion is related to the physical size ofthe ignition source, the duration of the ignition source, and the energycontent of the ignition source. The thermally reactive reagent 32 in thenon-flammable gas mixture 30 will react in a localized, relatively smallvolume that is related to the size and energy content of the ignitionsource and the nature of the reaction (e.g., combustion and/or thermaldecomposition) of the thermally reactive reagent 32. The reaction volumemay be referred to as a reaction kernel and/or a combustion kernel. Thereaction volume may be less than 10 mL (milliliter), less than 1 mL, orless than 0.1 mL, and typically is greater than 0.000001 mL (1nanoliter). The total volume of the non-flammable gas mixture 30 incontact with the test article 20 is related to the size of the testarticle 20 (at least the size of the portion in contact with thenon-flammable gas mixture 30). Some test articles may be very large(e.g., an aircraft wing). Typical volumes of the non-flammable gasmixture 30 include greater than 1 L (liter), greater than 10 L, greaterthan 100 L, or greater than 1,000 L, and typically is less than 100,000L (100 cubic meters). Thus, the reaction volume of the non-flammable gasmixture 30 may be less than one thousandth or less than one millionth ofthe total volume of the non-flammable gas mixture 30.

Because of the small reaction volume of the non-flammable gas mixture 30and because the thermally reactive reagent 32 may be included in thenon-flammable gas mixture 30 at a volume concentration of less than 10%(or less than 1%), the indicator species (e.g., the thermally reactivereagent 32 and/or the reaction product 38) may have a change inconcentration, relative to the non-flammable gas mixture 30 before theignition risk event, that may be in the range of parts per million orparts per billion. Hence, the detection device 50 may be configured tomeasure concentrations and/or absolute changes in concentrations at thelevel of parts per million or parts per billion.

Detection devices 50 may be high sensitivity gas analysis devicesadapted to measure the (potentially reacted) non-flammable gas mixture30. For example, illustrated in more detail in FIG. 2, the detectiondevice 50 may be a gas sampling detection device 52 such as a massspectrometer, a gas chromatograph, or a gas chromatography massspectrometer. As another example, illustrated in more detail in FIG. 3,the detection device 50 may be an optical detection device 58 such as anoptical spectrometer (that may measure absorbance, transmittance,reflectance, scattering, spectrum, luminescence, fluorescence, and/orphosphorescence), a laser-induced fluorescence (LIF) apparatus, a planarlaser-induced fluorescence (PLIF) apparatus, a laser-excited atomicfluorescence (LEAF) apparatus, and a Fourier transform infrared (FTIR)spectrometer.

As shown in FIG. 2, the gas sampling detection device 52 (e.g., the massspectrometer, the gas chromatograph, or the gas chromatography massspectrometer) may be configured to sample a portion (or the entirety) ofthe non-flammable gas mixture 30 after the ignition risk event may causethe ignition source 24 at the test article 20 and the consequentreaction of the reaction volume of the non-flammable gas mixture 30. Thegas sampling detection device 52 may be configured to sample unreactednon-flammable gas mixture 30 and/or the non-flammable gas mixture 30before the ignition risk event. The gas sampling detection device 52 maybe fluidically connected to the test chamber 12 via a gas sample port 54of the test chamber 12. The flow path from the test chamber 12 to thegas sampling detection device 52 may include a valve 18 that isconfigured to control the flow of the non-flammable gas mixture 30.

A mass spectrometer is an analytical instrument that analyzes a sampleby ionizing chemical species in the sample and subjecting the ionizedspecies to electric and magnetic fields to identify mass to chargeratios of the ionized species. The ionized species typically arefragments of the molecular species of the sample. The chemical speciesmay be identified by the mass to charge ratios and/or the pattern ofionized fragments.

A gas chromatograph is an analytical instrument that separates and/oranalyzes gaseous and/or vaporous chemical species in a sample (and/orderived from a sample). Gas chromatographs typically detect theretention time of the chemical species travelling through a column.

A gas chromatography mass spectrometer includes a gas chromatographcolumn input stage and a mass spectrometer detection stage. The gaschromatograph input provides separation of components of the sampleprior to mass spectrometry such that gas components may be morespecifically determined (e.g., by retention time and mass to chargeratio) than with an ordinary gas chromatograph (e.g., by retention time)or an ordinary mass spectrometer (e.g., by mass to charge ratio).

As also shown in FIG. 2, the optical detection device 58 (e.g., theoptical spectrometer, the LIF apparatus, the PLIF apparatus, the LEAFapparatus, or the FTIR spectrometer) may be configured to sample andmeasure a portion (or the entirety) of the non-flammable gas mixture 30in a configuration similar to the gas sampling detection device 52.Additionally or alternatively, and as shown in FIG. 3, the opticaldetection device 58 may be configured to measure the non-flammable gasmixture 30 in situ, proximate to the test article 20.

The optical detection device 58 may include one or more componentswithin the optional test chamber 12 and may include one or morecomponents outside of the test chamber 12. For components locatedoutside of the test chamber 12, those components may be in opticalcommunication with the non-flammable gas mixture 30 in the test chamber12 via a window 64 in the test chamber 12 (e.g., a transparent wall).

The optical detection device 58 generally includes a light source 60 andan optical detector 62. The light source 60 is configured to interrogatethe non-flammable gas mixture 30 in the test chamber 12 and/or proximateto the test article 20 with an input light beam 66. The light source 60may include, and/or may be, a laser, a lamp, or an LED (light emittingdiode). The light source 60 may generate and/or the input light beam 66may include light with a wavelength in the ultraviolet (UV), visible,infrared (IR), and/or far infrared (FIR). For example, the light mayhave a wavelength greater than 100 nm (nanometers), 200 nm, greater than400 nm, greater than 600 nm, greater than 800 nm, greater than 2,000 nm,greater than 10,000 nm, less than 20,000 nm, less than 4,000 nm, lessthan 1,000 nm, less than 800 nm, less than 400 nm, and/or less than 300nm.

The optical detector 62 is configured to detect output light 68 from the(potentially reacted) non-flammable gas mixture 30 due to interactionwith the input light beam 66. The optical detector 62 may be sensitiveto light, and the output light 68 may have a wavelength in theultraviolet (UV), visible, infrared (IR), and/or far infrared (FIR). Forexample, the light may have a wavelength greater than 100 nm(nanometers), 200 nm, greater than 400 nm, greater than 600 nm, greaterthan 800 nm, greater than 2,000 nm, greater than 10,000 nm, less than20,000 nm, less than 4,000 nm, less than 1,000 nm, less than 800 nm,less than 400 nm, and/or less than 300 nm. The optical detector 62 maybe configured to detect the light of the input light beam 66 (e.g., fortransmission, absorbance, reflection, and scattering (nephelometry)measurements) and/or to reject the light of the input light beam 66(e.g., for luminescence, fluorescence, phosphorescence, and Ramanscattering measurements).

The optical detection device 58 may be configured to determinetransmission, reflection, absorption, scattering, luminescence,fluorescence, and/or phosphorescence of the non-flammable gas mixture30. In scattering, fluorescence, or phosphorescence mode, the opticaldetection device 58 has the light source 60 and the optical detector 62arranged non-collinearly, for example facing orthogonal light paths asshown in the example of FIG. 3 (with the optical detector 62 in solidlines). The optical detector 62 is configured to detect the output light68 that emerges from a sample of the non-flammable gas mixture 30 due tointeraction with the input light beam 66. For example, the output light68 may be due to scattering (e.g., Rayleigh or Raman scattering) and/oroptical emission (e.g., luminescence, fluorescence, and/orphosphorescence emission).

In transmission mode (e.g., for transmission or absorbancemeasurements), the optical detection device 58 is arranged such that thenon-flammable gas mixture 30 (or a sample of the non-flammable gasmixture 30) is optically between the light source 60 and the opticaldetector 62. For example, the light source 60 and the optical detector62 may be on opposite sides of the test chamber 12 as shown in FIG. 3(with the optical detector 62 in dotted lines). The optical detector 62is configured to detect the input light beam 66 that is transmittedthrough the sample of the non-flammable gas mixture 30. The input lightbeam 66 is transformed by interaction with the sample into the outputlight 68 in the form of a transmitted beam and/or an attenuated beam.

A LIF apparatus, a PLIF apparatus, and a LEAF apparatus are analyticalapparatuses configured to illuminate a sample containing an indicatorspecies (a molecule or atom) with laser light (the input light beam 66)tuned to excite fluorescence in the indicator species. The fluorescenceemission (the output light 68) is detected by the optical detector 62that is configured to detect light of the fluorescence emission andreject light of the input light beam 66. The spectra, intensity, andlifetime of the fluorescence emission may provide sensitivediscrimination of the indicator species over other background speciesand/or may provide information about the state of the indicator speciesand/or the local environment near the indicator species. In a PLIFapparatus, the laser light is scanned and/or spread into a light sheetand the fluorescence emission may be detected by an imaging detector.

A FTIR spectrometer is an analytical instrument that measures theinfrared absorption or emission spectrum of a sample. The FTIRspectrometer simultaneously collects high spectral resolution data overa wide spectral range. The high spectral resolution and wide spectralrange may provide sensitive discrimination of different indicatorspecies in the sample.

Returning generally to FIG. 1, the test system 10 may include acontroller 70 configured and/or programmed to control the operation ofthe test system 10 as a whole and/or individual components of the testsystem 10. The controller 70 may be configured and/or programmed (a) todischarge the energy source 26 to apply the energy discharge to the testarticle 20, (b) to measure the presence and/or amount of the indicatorspecies in the non-flammable gas mixture 30 with the detection device50, and/or (c) to determine an incendivity of the test article 20 inresponse to the energy discharge based upon the presence and/or amountof the indicator species. The controller 70 may be configured and/orprogrammed to operate valves 18 at the gas inlet port 14, the gas outletport 16, and/or at the gas sample port 54 to respectively control gasentering the test chamber 12, gas exiting the test chamber 12, and/orgas sampled by the detection device 50. The controller 70 may beconfigured and/or programmed to perform any of the methods describedherein. The controller 70 may include a computer, an embeddedcontroller, a programmable logic device, and/or a field-programmablegate array.

The test system 10 may include a controlled ignition source 72 that isconfigured to discharge energy (e.g., create an ignition source such asan arc) in the non-flammable gas mixture 30 sufficient to react thethermally reactive reagent 32 in the non-flammable gas mixture 30. Thecontrolled ignition source 72 may be configured to discharge energy intothe non-flammable gas mixture 30 in the optional test chamber 12 and/orat a position configured to be detected by the detection device 50(e.g., upstream in a flowing stream of the non-flammable gas mixture30).

The controlled ignition source 72 may be controlled by the controller70. For example, the controller may be configured and/or programmed toinitiate the energy discharge of the controlled ignition source 72and/or to terminate the energy discharge of the controlled ignitionsource 72.

The controlled ignition source 72 may be configured to discharge apredetermined amount of energy into the non-flammable gas mixture 30and/or an amount of energy configured to cause the thermally reactivereagent 32 to react. A controlled ignition source 72 that provides apredetermined and/or controllable amount of energy into thenon-flammable gas mixture 30 may be referred to as a controlled-energyignition source. The controlled ignition source 72 may discharge anenergy of less than 1,000 μl, less than 500 μl, less than 200 μl, lessthan 100 μl, greater than 10 μl, greater than 50 μl, greater than 100μl, greater than 200 μl, and/or about 200 μl. The controlled ignitionsource 72 may produce an electrical arc, a spark, a hot surface, a hotparticle ejection, an electrostatic discharge, and/or a flame.

FIG. 4 illustrates incendivity test methods 100. Methods 100 may bereferred to as flammability test methods, ignition risk test methods,and/or ignition hazard test methods. Methods 100 include contacting 102a test article (such as test article 20) with a non-flammable gasmixture (such as non-flammable gas mixture 30), applying 104 an energydischarge to the test article while the test article is in contact withthe non-flammable gas mixture, then measuring 106 an amount of one ormore components (e.g., indicator species as described herein) of thenon-flammable gas mixture to determine the response of the non-flammablegas mixture to the energy discharge, and determining 108 an incendivityof the test article in response to the energy discharge based upon theamount of the one or more components measured. Methods 100 may includeusing the non-flammable gas mixture to test the incendivity to the testarticle and/or using the test system 10 to test the incendivity of thetest article.

Contacting 102 may include contacting the test article with thenon-flammable gas mixture in a test chamber (such as test chamber 12).Contacting 102 may include filling the test chamber with thenon-flammable gas mixture and/or creating suitable conditions for thenon-flammable gas mixture in the test chamber. Suitable conditions suchas pressure, temperature, and simulated operating environments arediscussed further herein with respect to the non-flammable gas mixture30.

Contacting 102 may include flowing a stream of the non-flammable gasmixture over the test article such that the non-flammable gas mixturesubstantially or completely displaces other gases from contact with thetest article (at least at a portion of the test article). The stream ofthe non-flammable gas mixture may contact a portion or essentially theentirety of the test article. The stream of the non-flammable gasmixture may be a recirculating or non-recirculating stream. Inembodiments where the test article is contacted by a stream of thenon-flammable gas mixture, the gas analysis (e.g., measuring 106) isgenerally performed at the point of an ignition source (e.g., theignition source 24) generated by the applying 104 the energy dischargeor downstream from the ignition source. For example, gas analysis may beperformed downstream from the test article. If the stream of thenon-flammable gas mixture does not recirculate, the gas analysis isdownstream from the ignition source and/or the test article.

The non-flammable gas mixture includes a thermally reactive reagent,such as the thermally reactive reagent 32, that reacts to an ignitionsource (such as ignition source 24) generated by the applying 104 theenergy discharge. The thermally reactive reagent reacts to produce oneor more reaction products such as reaction products 38. Thenon-flammable gas mixture may include an oxidant (such as oxidant 34)that reacts with the thermally reactive reagent, and/or may include adiluent such as diluent 36.

Methods 100 may include preparing the non-flammable gas mixture bymixing the thermally reactive reagent with one or more oxidants and oneor more diluents. Methods 100 may include preparing the non-flammablegas mixture by mixing two or more thermally reactive reagents.Contacting 102 and/or preparing the non-flammable gas mixture mayinclude contacting, selecting, formulating, and/or preparing a mixtureof a combustion fuel and molecular oxygen, a mixture of a halocarbon andmolecular oxygen, and/or other mixtures described herein with respect tothe non-flammable gas mixture 30 (e.g., 2% ethylene in air, 1%chloroethane in air, 0.01% methyl bromide in air).

Applying 104 the energy discharge includes applying the energy dischargeinto, at, and/or to the test article to test whether the dischargedenergy generates an ignition source at the test article that issufficient to react the non-flammable gas mixture in contact with thetest article. Applying 104 the energy discharge may also be referred toas activating the test article, energizing the test article, and/orignition hazard simulation. The energy discharge may simulate and/or maybe actual operating conditions that the test article may experience suchas a lightning strike, a static electrical charge discharge, heat,and/or a spark. Applying 104 the energy discharge may include applying asimulated lightning strike to the test article, applying a voltageacross the test article (e.g., a voltage greater than 1 kV (kilovolts)or greater than 5 kV, and generally less than 100 kV), supplying anelectrical current through the test article (e.g., a current greaterthan 1 A (amperes) or greater than 10 A, and generally less than 100,000A). The energy discharge may have a peak power of greater than 1 kW(kilowatts) or greater than 10 kW, and generally less than 10,000 kW.The energy discharge may be relatively short, for example, having aduration of less than 1 second, less than 0.1 seconds, less than 0.01seconds, or less than 0.001 seconds, and generally longer than 1nanosecond. Applying 104 the energy discharge may include heating thetest article (e.g., heating a region of the test article), for example,heating to a temperature greater than 100° C., greater than 200° C., orgreater than 300° C., and generally less than 2,000° C.

Measuring 106 includes measuring the amount of the components of thenon-flammable gas mixture that represents the amount of the thermallyreactive reagent in the non-flammable gas mixture that reacted inresponse to applying 104 the energy discharge. The amount of thecomponents of the non-flammable gas mixture may be a proxy of the amountof the thermally reactive reagent in the (potentially) reactednon-flammable gas mixture. Measuring 106 may include measuring an amountof the thermally reactive reagent and/or the oxidant remaining in thenon-flammable gas mixture after applying 104 the energy discharge.Measuring 106 may include measuring an amount of the reaction productproduced by thermal reaction (e.g., combustion and/or thermaldecomposition) of the thermally reactive reagent after applying 104 theenergy discharge. Because non-flammable gas mixture may includerelatively little reaction product before applying 104 the energydischarge, measuring the amount of the reaction product may be subjectto less error and/or have higher precision than measuring the amount ofthe thermally reactive reagent or the oxidant. Additionally oralternatively, the relative change of concentration (after applying 104the energy discharge to before applying 104 the energy discharge) of thereaction product may be substantially greater than the correspondingrelative change of concentration of the thermally reactive reagent orthe oxidant.

Measuring 106 generally includes measuring the components of thenon-flammable gas mixture with a high sensitivity technique, forexample, a technique sensitive to low concentrations and/or smallchanges (e.g., concentrations and/or absolute changes of parts permillion or parts per billion). Measuring 106 may include measuring by agas analysis technique such as mass spectrometry, gas chromatography, orgas chromatography mass spectrometry. Measuring 106 may includemeasuring by an optical technique selected from the group consisting ofoptical spectrometry, optical absorbance, optical transmittance, opticalreflectance, nephelometry, luminescence, fluorescence, phosphorescence,laser-induced fluorescence, planar laser-induced fluorescence,laser-excited atomic fluorescence, and Fourier transform infraredspectrometry.

Determining 108 incendivity may include determining the presence and/orabsence of a thermal reaction in response to the energy discharge (e.g.,combustion or thermal breakdown of the thermally reactive reagent 32).Determining 108 incendivity may include determining whether thermalreaction (combustion or thermal breakdown) occurred above a thresholdlevel (e.g., combustion or breakdown products are present at aconcentration greater than a threshold level). Determining 108incendivity may include determining the presence and/or absence of anignition source with greater than a threshold energy that was generatedin response to the energy discharge. Determining 108 incendivity mayinclude comparing a parameter related to the amount of thermallyreactive reagent that reacted (e.g., the concentration of the thermallyreactive reagent and/or the concentration of the reaction product) to apredefined threshold. The threshold levels of reaction and/or energy maybe representative of an ignition source that would be an ignitionhazard. Hence, determining 108 may include determining that the testarticle generated an ignition hazard in response to the energydischarge. Determining 108 may include determining a level ofincendivity of the test article subject to the energy discharge basedupon the amount of thermally reactive reagent that reacted (and/or aproxy thereof such as the concentration of the reaction product and/orthe oxidant).

Methods 100 may include verifying 110 that the non-flammable gas mixturereacts to a thermal input by discharging a controlled ignition source(such as controlled ignition source 72) in the non-flammable gas mixtureand after the controlled ignition source discharge, measuring the amountof one or more components (e.g., the indicator species) of thenon-flammable gas mixture to verify that at least a portion of thethermally reactive reagent reacted in response to discharging thecontrolled ignition source. Verifying 110 may be performed before orafter applying 104 the energy discharge and measuring 106 the componentsof the potentially reacted non-flammable gas mixture. Verifying 110 maybe performed in the optional test chamber.

Verifying 110 with a reliable ignition source such as the controlledignition source verifies that components of the corresponding testsystem (such as detection device 50) function properly. Additionally oralternatively, verifying 110 may provide a reference amount of thermallyreactive reagent (or proxy such as concentration of the reactionproduct) that is generated in response to an ignition source (optionallyan ignition source of predetermined energy).

Examples of inventive subject matter according to the present disclosureare described in the following enumerated paragraphs.

A1. An incendivity test method comprising:

contacting a test article with a non-flammable gas mixture that includesa thermally reactive reagent;

applying an energy discharge to the test article while the test articleis in contact with the non-flammable gas mixture;

after applying the energy discharge, measuring an amount of one or morecomponents of the non-flammable gas mixture that represents an amount ofthe thermally reactive reagent that reacted in response to applying theenergy discharge; and

determining an incendivity of the test article in response to the energydischarge based upon the amount of the thermally reactive reagent thatreacted in response to applying the energy discharge.

A2. The method of paragraph A1, wherein the contacting the test articleincludes contacting the test article in a test chamber with thenon-flammable gas mixture.

A2.1. The method of paragraph A2, wherein the contacting includesfilling the test chamber with the non-flammable gas mixture, andoptionally wherein the filling includes filing the test chamber with thenon-flammable gas mixture to a pressure of at least one of greater than50 kPa, greater than 70 kPa, greater than 90 kPa, greater than 100 kPa,less than 200 kPa, less than 150 kPa, less than 120 kPa, less than 100kPa, about 70 kPa, and about 100 kPa.

A3. The method of any of paragraphs A1-A2.1, wherein the contactingincludes contacting the test article with the non-flammable gas mixtureat a pressure of at least one of greater than 50 kPa, greater than 70kPa, greater than 90 kPa, greater than 100 kPa, less than 200 kPa, lessthan 150 kPa, less than 120 kPa, less than 100 kPa, about 70 kPa, andabout 100 kPa.

A4. The method of any of paragraphs A1-A3, wherein the contactingincludes immersing the test article in the non-flammable gas mixture,and optionally flowing a stream of the non-flammable gas mixture overthe test article.

A5. The method of any of paragraphs A1-A4, wherein the thermallyreactive reagent is configured to react in response to an ignitionsource to produce a reaction product.

A6. The method of any of paragraphs A1-A5, wherein the thermallyreactive reagent includes, optionally is, at least one of a thermallyreactive gas and a thermally reactive aerosol.

A7. The method of any of paragraphs A1-A6, wherein the non-flammable gasmixture is a mixture that is too lean to support self-propagatingcombustion of the thermally reactive reagent.

A8. The method of any of paragraphs A1-A7, wherein the non-flammable gasmixture has a concentration of the thermally reactive reagent that isbelow a lean ignition limit.

A9. The method of any of paragraphs A1-A8, wherein the thermallyreactive reagent is at least one of gaseous and vaporous.

A10. The method of any of paragraphs A1-A9, wherein the non-flammablegas mixture includes an aerosol of the thermally reactive reagent.

A11. The method of any of paragraphs A1-A10, wherein the non-flammablegas mixture includes a plurality of thermally reactive reagents.

A11.1. The method of paragraph A11, wherein each of the thermallyreactive reagents is configured to react in response to a differentignition source to produce a corresponding reaction product.

A12. The method of any of paragraphs A1-A11.1, wherein the thermallyreactive reagent is a combustion fuel, optionally selected from thegroup consisting of a hydrocarbon fuel, a flammable gas, molecularhydrogen, methane, propane, gasoline, kerosene, and ethylene.

A13. The method of any of paragraphs A1-A12, wherein the thermallyreactive reagent is configured to thermally decompose.

A14. The method of any of paragraphs A1-A13, wherein the thermallyreactive reagent is a halocarbon, optionally selected from the groupconsisting of an alkyl halide, a chlorocarbon, a fluorocarbon, abromocarbon, a chlorofluorocarbon, chloroethane, and methyl bromide.

A15. The method of any of paragraphs A1-A14, further comprisingpreparing the non-flammable gas mixture by mixing the thermally reactivereagent with one or more of an oxidant, a diluent, and another thermallyreactive reagent.

A16. The method of any of paragraphs A1-A15, wherein the non-flammablegas mixture includes an oxidant.

A16.1. The method of paragraph A16, wherein the thermally reactivereagent is configured to react with the oxidant to produce a/thereaction product.

A16.2. The method of any of paragraphs A16-A16.1, wherein thenon-flammable gas mixture includes a plurality of thermally reactivereagents and each of the thermally reactive reagents is configured toreact with the oxidant in response to a different ignition source toproduce a corresponding reaction product.

A16.3. The method of any of paragraphs A16-A16.2, wherein thenon-flammable gas mixture includes a plurality of thermally reactivereagents and wherein the non-flammable gas mixture includes a pluralityof corresponding oxidants wherein each corresponding oxidant isconfigured to react with at least one of the thermally reactive reagentsto produce a/the corresponding reaction product.

A16.4. The method of any of paragraphs A16-A16.3, wherein the oxidant isat least one of gaseous and vaporous.

A16.5. The method of any of paragraphs A16-A16.4, wherein thenon-flammable gas mixture includes an aerosol of the oxidant.

A16.6. The method of any of paragraphs A16-A16.5, where the oxidantincludes one or more species selected from the group consisting ofmolecular oxygen, nitrous oxide, and hydrogen peroxide.

A17. The method of any of paragraphs A1-A16.6, wherein the non-flammablegas mixture includes a diluent.

A17.1. The method of paragraph A17, wherein the diluent is configurednot to react with the thermally reactive reagent.

A17.2. The method of any of paragraphs A17-A17.1, wherein the diluentincludes one or more species selected from the group consisting of aninert gas, nitrogen, argon, and helium.

A18. The method of any of paragraphs A1-A17.2, wherein a/the reactionproduct is selected from the group consisting of water, carbon dioxide,carbon monoxide, formaldehyde, hydrochloric acid, hydrofluoric acid,hydrobromic acid, carbonyl difluoride, carbonyl dichloride, carbonyldibromide, molecular fluorine, molecular chlorine, and molecularbromine.

A19. The method of any of paragraphs A1-A18, wherein the non-flammablegas mixture includes a volume fraction of chloroethane of about 1% inair.

A20. The method of any of paragraphs A1-A19, wherein the non-flammablegas mixture includes a volume fraction of methyl bromide of about 0.01%in air.

A21. The method of any of paragraphs A1-A20, wherein the non-flammablegas mixture includes a volume fraction of ethylene of less than 2.7%,less than 2.5%, about 2%, and/or greater than 0.1% in air.

A22. The method of any of paragraphs A1-A21, wherein the applying theenergy discharge includes applying a simulated lightning strike to thetest article.

A23. The method of any of paragraphs A1-A22, wherein the applying theenergy discharge includes 1 generating an arc at the test article.

A24. The method of any of paragraphs A1-A23, wherein the applying theenergy discharge includes applying a voltage across the test article,and optionally wherein the voltage is greater than 1 kV or greater than5 kV.

A25. The method of any of paragraphs A1-A24, wherein the applying theenergy discharge includes supplying a current through the test article,and optionally wherein the current is greater than 1 A or greater than10 A.

A26. The method of any of paragraphs A1-A25, wherein the energydischarge has a peak power of greater than 1 kW or greater than 10 kW.

A27. The method of any of paragraphs A1-A26, wherein the applying theenergy discharge includes heating the test article.

A28. The method of any of paragraphs A1-A27, wherein the applying theenergy discharge generates an ignition source at the test articlesufficient to react the thermally reactive reagent to produce a/thereaction product.

A29. The method of any of paragraphs A1-A28, wherein the measuringincludes measuring an amount of the thermally reactive reagent remainingin the non-flammable gas mixture after applying the energy discharge.

A30. The method of any of paragraphs A1-A29, wherein the measuringincludes measuring an amount of an/the oxidant remaining in thenon-flammable gas mixture after applying the energy discharge.

A31. The method of any of paragraphs A1-A30, wherein the measuringincludes measuring an amount of a/the reaction product produced bythermal reaction of the thermally reactive reagent after applying theenergy discharge.

A32. The method of any of paragraphs A1-A31, wherein the measuringincludes measuring by a gas analysis technique selected from the groupconsisting of mass spectrometry, gas chromatography, and gaschromatography mass spectrometry.

A33. The method of any of paragraphs A1-A32, wherein the measuringincludes measuring by an optical technique selected from the groupconsisting of optical spectrometry, optical absorbance, opticaltransmittance, optical reflectance, nephelometry, luminescence,fluorescence, phosphorescence, laser-induced fluorescence, planarlaser-induced fluorescence, laser-excited atomic fluorescence, andFourier transform infrared spectrometry.

A34. The method of any of paragraphs A1-A33, wherein the determining theincendivity includes comparing a parameter related to the amount ofthermally reactive reagent that reacted to a predefined threshold.

A35. The method of any of paragraphs A1-A34, wherein the determining theincendivity includes determining that the test article generated anignition hazard in response to the energy discharge based upon whetherthe amount of thermally reactive reagent that reacted is greater thanthe predefined threshold.

A36. The method of any of paragraphs A1-A35, wherein the determining theincendivity includes determining a level of incendivity based upon theamount of thermally reactive reagent that reacted.

A37. The method of any of paragraphs A1-A36, further comprisingverifying the non-flammable gas mixture reacts to a thermal input bydischarging a controlled ignition source in the non-flammable gasmixture and, after the controlled ignition source discharge, measuringthe amount of one or more components of the non-flammable gas mixture toverify that at least a portion of the thermally reactive reagent reactedin response to discharging the controlled ignition source.

A37.1. The method of paragraph A37, wherein the verifying is performedafter the determining.

A37.2. The method of any of paragraphs A37-A37.1, wherein the controlledignition source is discharged within a/the test chamber with the testarticle.

A37.3. The method of any of paragraphs A37-A37.2, wherein thedischarging the controlled ignition source discharges an energy of lessthan 1,000 μl, less than 500 μl, less than 200 μl, less than 100 μl,greater than 10 μl, greater than 50 μl, greater than 100 μl, greaterthan 200 μl, and/or about 200 μl.

A37.4. The method of any of paragraphs A37-A37.3, wherein the controlledignition source produces, optionally is, at least one of an electricalarc, a spark, a hot surface, a hot particle ejection, an electrostaticdischarge, and a flame.

A38. The method of any of paragraphs A1-A37.4, wherein the test articleis a solid form and optionally includes one or more of metal, aluminum,plastic, and fiber-reinforced composite material.

A39. The method of any of paragraphs A1-A38, wherein the test article isan aerospace component, and optionally at least one of an aircraft skin,an aircraft frame, a wing, a fuel handling component, a fuel system, afuel tank, a fuel pump, and an electrical enclosure.

B1. An incendivity test system, optionally an aerospace componentincendivity test system, comprising:

a test chamber;

a non-flammable gas mixture in the test chamber, wherein thenon-flammable gas mixture includes a thermally reactive reagent that isformulated to thermally react to produce a reaction product;

a test article in the test chamber in contact with the non-flammable gasmixture;

an energy source configured to apply an energy discharge to the testarticle; and

a detection device configured to measure an amount of one or moreindicator species selected from the group consisting of a component ofthe non-flammable gas mixture and the reaction product.

B2. The system of paragraph B1, wherein the thermally reactive reagentincludes, optionally is, at least one of a thermally reactive gas and athermally reactive aerosol.

B3. The system of any of paragraphs B1-B2, wherein the non-flammable gasmixture is a mixture that is too lean to support self-propagatingcombustion of the thermally reactive reagent.

B4. The system of any of paragraphs B1-B3, wherein the non-flammable gasmixture has a concentration of the thermally reactive reagent that isbelow a lean ignition limit.

B5. The system of any of paragraphs B1-B4, wherein the thermallyreactive reagent is at least one of gaseous and vaporous.

B6. The system of any of paragraphs B1-B5, wherein the non-flammable gasmixture includes an aerosol of the thermally reactive reagent.

B7. The system of any of paragraphs B1-B6, wherein the thermallyreactive reagent is a combustion fuel, optionally selected from thegroup consisting of a hydrocarbon fuel, a flammable gas, molecularhydrogen, methane, propane, gasoline, kerosene, and ethylene.

B8. The system of any of paragraphs B1-B7, wherein the thermallyreactive reagent is configured to thermally decompose.

B9. The system of any of paragraphs B1-B8, wherein the thermallyreactive reagent is a halocarbon, optionally selected from the groupconsisting of an alkyl halide, a chlorocarbon, a fluorocarbon, abromocarbon, a chlorofluorocarbon, chloroethane, and methyl bromide.

B10. The system of any of paragraphs B1-B9, wherein the non-flammablegas mixture includes a plurality of thermally reactive reagents.

B10.1. The system of paragraph B10, wherein each of the thermallyreactive reagents is configured to react in response to a differentignition source to produce a corresponding reaction product.

B11. The system of any of paragraphs B1-B10.1, wherein the non-flammablegas mixture includes an oxidant.

B11.1. The system of paragraph B11, wherein the thermally reactivereagent is configured to react with the oxidant to produce the reactionproduct.

B11.2. The system of any of paragraphs B11-B11.1, wherein thenon-flammable gas mixture includes a plurality of thermally reactivereagents and each of the thermally reactive reagents is configured toreact with the oxidant in response to a different ignition source toproduce a corresponding reaction product.

B11.3. The system of any of paragraphs B11-B11.2, wherein thenon-flammable gas mixture includes a plurality of thermally reactivereagents and wherein the non-flammable gas mixture includes a pluralityof corresponding oxidants wherein each corresponding oxidant isconfigured to react with at least one of the thermally reactive reagentsto produce a/the corresponding reaction product.

B11.4. The system of any of paragraphs B11-B11.3, wherein the oxidant isat least one of gaseous and vaporous.

B11.5. The system of any of paragraphs B11-B11.4, wherein thenon-flammable gas mixture includes an aerosol of the oxidant.

B11.6. The system of any of paragraphs B11-B11.5, where the oxidantincludes one or more species selected from the group consisting ofmolecular oxygen, nitrous oxide, and hydrogen peroxide.

B12. The system of any of paragraphs B1-B11.6, wherein the non-flammablegas mixture includes a diluent.

B12.1. The system of paragraph B12, wherein the diluent is configurednot to react with the thermally reactive reagent.

B12.2. The system of any of paragraphs B12-B12.1, wherein the diluentincludes one or more species selected from the group consisting of aninert gas, nitrogen, argon, and helium.

B13. The system of any of paragraphs B1-B12.2, wherein the reactionproduct is selected from the group consisting of water, carbon dioxide,carbon monoxide, formaldehyde, hydrochloric acid, hydrofluoric acid,hydrobromic acid, carbonyl difluoride, carbonyl dichloride, carbonyldibromide, molecular fluorine, molecular chlorine, and molecularbromine.

B14. The system of any of paragraphs B1-B13, wherein the non-flammablegas mixture includes a volume fraction of chloroethane of about 1% inair.

B15. The system of any of paragraphs B1-B14, wherein the non-flammablegas mixture includes a volume fraction of methyl bromide of about 0.01%in air.

B16. The system of any of paragraphs B1-B15, wherein the non-flammablegas mixture includes a volume fraction of ethylene of less than 2.7%,less than 2.5%, about 2%, and/or greater than 0.1% in air.

B17. The system of any of paragraphs B1-B16, wherein the detectiondevice is a gas sampling device, optionally selected from the groupconsisting of a mass spectrometer, a gas chromatograph, and a gaschromatography mass spectrometer.

B18. The system of any of paragraphs B1-B17, wherein the detectiondevice is an optional detection device, optionally selected from thegroup consisting of an optical spectrometer, a fluorescencespectrometer, a laser-induced fluorescence apparatus, a planarlaser-induced fluorescence apparatus, a laser-excited atomicfluorescence apparatus, and a Fourier transform infrared spectrometer.

B19. The system of any of paragraphs B1-B18, wherein the energy sourceis at least one of a lightning strike simulator, an electrical powersource, an electrical voltage source, and an electrical current source.

B20. The system of any of paragraphs B1-B19, further comprising acontroller configured to discharge the energy source to apply the energydischarge to the test article, configured to measure the presence and/oramount of the indicator species, and configured to determine anincendivity of the test article in response to the energy dischargebased upon the presence and/or amount of the indicator species.

B20.1. The system of paragraph B20, wherein the controller is programmedto perform the incendivity test method of any of paragraphs A1-A39.

B21. The system of any of paragraphs B1-B20.1, further comprising a gassource configured to supply the non-flammable gas mixture to the testchamber and optionally wherein the gas source is connected to the testchamber via a gas inlet port of the test chamber and a valve that isconfigured to control a flow of the non-flammable gas mixture from thegas source to the test chamber.

B22. The system of any of paragraphs B1-B21, wherein the test article isa solid form and optionally includes one or more of metal, aluminum,plastic, and fiber-reinforced composite material.

B23. The system of any of paragraphs B1-B22, wherein the test article isan aerospace component, and optionally at least one of an aircraft skin,an aircraft frame, a wing, a fuel handling component, a fuel system, afuel tank, a fuel pump, and an electrical enclosure.

B24. The use of the incendivity test system of any of paragraphs B1-B23to test the incendivity of the test article in response to the energydischarge.

C1. The use of a non-flammable gas mixture to test the incendivity of atest article, optionally by applying an energy discharge to the testarticle while the test article is in contact with the non-flammable gasmixture and measuring an amount of one or more components of thenon-flammable gas mixture after applying the energy discharge todetermine the incendivity based upon the amount of the one or morecomponents of the non-flammable gas mixture that is measured.

C2. The use of paragraph C1, wherein the non-flammable gas mixtureand/or the test article are as recited in any of paragraphs A1-A39and/or B1-B23.

As used herein, the terms “adapted” and “configured” mean that theelement, component, or other subject matter is designed and/or intendedto perform a given function. Thus, the use of the terms “adapted” and“configured” should not be construed to mean that a given element,component, or other subject matter is simply “capable of” performing agiven function but that the element, component, and/or other subjectmatter is specifically selected, created, prepared, formed, implemented,utilized, programmed, and/or designed for the purpose of performing thefunction. It is also within the scope of the present disclosure thatelements, components, and/or other recited subject matter that isrecited as being adapted to perform a particular function mayadditionally or alternatively be described as being configured toperform that function, and vice versa. Similarly, subject matter that isrecited as being configured to perform a particular function mayadditionally or alternatively be described as being operative to performthat function.

As used herein, the phrase, “for example,” the phrase, “as an example,”and/or simply the term “example,” when used with reference to one ormore components, features, details, structures, embodiments, and/ormethods according to the present disclosure, are intended to convey thatthe described component, feature, detail, structure, embodiment, and/ormethod is an illustrative, non-exclusive example of components,features, details, structures, embodiments, and/or methods according tothe present disclosure. Thus, the described component, feature, detail,structure, embodiment, and/or method is not intended to be limiting,required, or exclusive/exhaustive; and other components, features,details, structures, embodiments, and/or methods, including structurallyand/or functionally similar and/or equivalent components, features,details, structures, embodiments, and/or methods, are also within thescope of the present disclosure.

As used herein, the phrases “at least one of” and “one or more of,” inreference to a list of more than one entity, means any one or more ofthe entities in the list of entities, and is not limited to at least oneof each and every entity specifically listed within the list ofentities. For example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently, “at least one of A and/or B”)may refer to A alone, B alone, or the combination of A and B.

As used herein, the singular forms “a”, “an” and “the” may be intendedto include the plural forms as well, unless the context clearlyindicates otherwise.

The various disclosed elements of systems and steps of methods disclosedherein are not required of all systems and methods according to thepresent disclosure, and the present disclosure includes all novel andnon-obvious combinations and subcombinations of the various elements andsteps disclosed herein. Moreover, any of the various elements and steps,or any combination of the various elements and/or steps, disclosedherein may define independent inventive subject matter that is separateand apart from the whole of a disclosed system or method. Accordingly,such inventive subject matter is not required to be associated with thespecific systems and methods that are expressly disclosed herein, andsuch inventive subject matter may find utility in systems and/or methodsthat are not expressly disclosed herein.

The invention claimed is:
 1. An incendivity test method comprising:contacting a test article with a non-flammable gas mixture, wherein thenon-flammable gas mixture includes a thermally reactive reagent;applying an energy discharge to the test article while the test articleis in contact with the non-flammable gas mixture; after applying theenergy discharge, measuring an amount of one or more components of thenon-flammable gas mixture that represents an amount of the thermallyreactive reagent that reacted in response to applying the energydischarge; and determining an incendivity of the test article inresponse to the energy discharge based upon the amount of the thermallyreactive reagent that reacted in response to applying the energydischarge.
 2. The method of claim 1, wherein the non-flammable gasmixture is a mixture that is too lean to support self-propagatingcombustion of the thermally reactive reagent.
 3. The method of claim 1,wherein the applying the energy discharge includes applying a simulatedlightning strike to the test article.
 4. The method of claim 1, whereinthe energy discharge has a peak power of greater than 1 kW (kilowatt).5. The method of claim 1, wherein the measuring includes measuring anamount of a reaction product produced by thermal reaction of thethermally reactive reagent after applying the energy discharge.
 6. Themethod of claim 1, wherein the measuring includes measuring by a gasanalysis technique selected from the group consisting of massspectrometry, gas chromatography, and gas chromatography massspectrometry.
 7. The method of claim 1, wherein the measuring includesmeasuring by an optical technique selected from the group consisting ofoptical spectrometry, optical absorbance, optical transmittance, opticalreflectance, nephelometry, luminescence, fluorescence, phosphorescence,laser induced fluorescence, planar laser induced fluorescence, laserexcited atomic fluorescence, and Fourier transform infraredspectrometry.
 8. The method of claim 1, wherein the non-flammable gasmixture includes a plurality of thermally reactive reagents, whereineach of the thermally reactive reagents is configured to react inresponse to a different ignition source to produce a correspondingreaction product.
 9. The method of claim 1, wherein the thermallyreactive reagent is a combustion fuel.
 10. The method of claim 1,wherein the thermally reactive reagent is configured to thermallydecompose.
 11. The method of claim 1, wherein the thermally reactivereagent is a halocarbon.
 12. The method of claim 1, wherein thecontacting includes immersing the test article in the non-flammable gasmixture.
 13. The method of claim 1, wherein the contacting includesflowing a stream of the non-flammable gas mixture over the test article.14. The method of claim 13, wherein the flowing includes recirculatingthe non-flammable gas mixture over the test article.
 15. The method ofclaim 1, further comprising preparing the non-flammable gas mixture bymixing the thermally reactive reagent with one or more of an oxidant, adiluent, and another thermally reactive reagent.
 16. The method of claim1, wherein the contacting includes contacting the test article with thenon-flammable gas mixture at a pressure of at least 50 kPa.
 17. Themethod of claim 1, wherein the thermally reactive reagent includes atleast one of a thermally reactive gas and a thermally reactive aerosol.18. The method of claim 1, wherein the non-flammable gas mixtureincludes an aerosol of the thermally reactive reagent.
 19. The method ofclaim 1, wherein the non-flammable gas mixture includes an oxidant, andwherein the non-flammable gas mixture includes a plurality of thermallyreactive reagents and each of the thermally reactive reagents isconfigured to react with the oxidant in response to a different ignitionsource to produce a corresponding reaction product.
 20. The method ofclaim 1, wherein the non-flammable gas mixture includes a plurality ofthermally reactive reagents, and wherein the non-flammable gas mixtureincludes a plurality of corresponding oxidants wherein eachcorresponding oxidant is configured to react with at least one of thethermally reactive reagents to produce a corresponding reaction product.21. The method of claim 1, wherein the determining the incendivityincludes comparing a parameter related to the amount of thermallyreactive reagent that reacted to a predefined threshold.
 22. The methodof claim 1, wherein the determining the incendivity includes determiningthat the test article generated an ignition hazard in response to theenergy discharge based upon whether the amount of thermally reactivereagent that reacted is greater than a predefined threshold.
 23. Themethod of claim 1, wherein the determining the incendivity includesdetermining a level of incendivity based upon the amount of thermallyreactive reagent that reacted.
 24. The method of claim 1, furthercomprising, before or after the applying the energy discharge and themeasuring the amount of one or more component, verifying thenon-flammable gas mixture reacts to a thermal input by discharging acontrolled ignition source in the non-flammable gas mixture and, afterthe controlled ignition source discharge, measuring the amount of one ormore components of the non-flammable gas mixture to verify that at leasta portion of the thermally reactive reagent reacted in response todischarging the controlled ignition source.
 25. The method of claim 24,wherein the verifying is performed after the determining the incendivityof the test article.
 26. The method of claim 1, wherein the test articleis at least one of an aircraft skin, an aircraft frame, an aircraftwing, a fuel handling component, a fuel system, a fuel tank, a fuelpump, and an electrical enclosure.
 27. An incendivity test systemcomprising: a non-flammable gas mixture, wherein the non-flammable gasmixture includes a thermally reactive reagent that is formulated tothermally react to produce a reaction product; a test article in contactwith the non-flammable gas mixture; an energy source configured to applyan energy discharge to the test article; and a detection deviceconfigured to measure an amount of one or more indicator speciesselected from the group consisting of a component of the non-flammablegas mixture and the reaction product.